1. Field of the Invention
The present invention relates to an oxygen concentrating apparatus for supplying an oxygen-concentrated gas of high oxygen concentration to an inhaler.
2. Description of the Related Art
An example of a conventional oxygen concentrating apparatus, is described in JP-A-2002-85566 Gazette (Patent Document 1) of the present inventors. The oxygen concentrating apparatus described therein has a compressor for taking in and supplying compressed air, a concentration means for increasing the oxygen concentration of the compressed air to thereby obtain an oxygen-concentrated gas, a gas tank for storing the oxygen-concentrated gas obtained from the concentration means, a gas outlet for supplying the oxygen-concentrated gas stored in the gas tank to an inhaling person, a respiration detection means for distinguishing the respiration state of the inhaling person, a continuous supply control means for continuously discharging the oxygen-concentrated gas from the gas outlet, and a synchronous supply control means for supplying a set quantity of the oxygen-concentrated gas to the gas outlet synchronized with inhalation of the inhaling person. On the other hand, the synchronous supply control means reduces, during exhalation time, the supply quantity of oxygen-concentrated gas to the gas outlet and stores, during that time, the oxygen-concentrated gas in a gas tank to thereby prepare for the next inhalation. The apparatus is adapted so that, in response to a supply setting within a range of oxygen-concentrated gas that can continuously be supplied by the compressor and concentration means, the continuous supply control means is adjusted correspondingly. Furthermore, in response to a supply setting exceeding the range of oxygen-concentrated gas that can be continuously supplied by the compressor and the concentration means, the synchronous supply control means is adjusted correspondingly. When respiration synchronous operation by the synchronous supply control means is in effect, a surplus quantity of the oxygen-concentrated gas produced during the exhalation period is stored in the gas tank and, during inhalation the stored quantity is added to the gas that is supplied. Consequently, it is possible to meet the demands of a supply setting exceeding the range of gas that can be continuously supplied.
Because the oxygen concentrating apparatus mentioned above is set so that, in response to a supply setting within the range of oxygen-concentrated gas that can be continuously supplied, the continuous supply control means fixes the output of the compressor to a constant value, and in response to a supply setting exceeding the range of oxygen-concentrated gas that can be continuously supplied the synchronous supply control means is adjusted, a problem arises in that a constant amount of electric power is consumed irrespective of the quantity of the oxygen-concentrated gas that is required and thus the electricity burden cost is large.